Field effect transistors (FETs) made of III-N materials such as gallium nitride (GaN) exhibit desirable properties for power switches, such as high bandgaps and high thermal conductivity compared to silicon FETs. Depletion mode GaN FETs are simpler and less expensive to fabricate than enhancement mode GaN FETs, and so may be desired for power switch semiconductor devices. However, it may also be desirable for a power switch to have a high impedance in an unpowered stated, which is not realized in a depletion mode GaN FET.